Apparatus for producing galvanic coatings



E. Gl-:MPE ,2,828,256

APPARATUS FOR PRoDUcING GALVANICl coATINGs March 25, 1958 2 Sheets-Sheet 1 Filed Feb. l2. 1954 E mw March 25, 1,958 E. GEMPE 2,328,255

APPARATUS FR PRODUCING GALVANIC COATINGS Filed Feb. 12, 1954 2 sheets-snaai 2 InverzZLo/-f EH'C Gem/m:

Any.

APPARATUS FR PRDUCING GALVANIC CATINGS assgnor to Wrttem- Erich Gempe, Bonn, Germany,

Ger-

1 Claim. (Cl. 2014-499) This invention relates to an apparatus for the production of galvanic coatings on objects of yall kinds which are subjected at diierent points to relatively heavy wear or which for other reasons have to be provided with a thicker layer of deposited metal over local zones than at other points. The invention relates particularly to the production of cutlery such as forks, spoons and the like which require locally thickened silver layers.

In the apparatus of this kind, there is established between an anode chamber which contains at least one anode, and a cathode chamber which contains the workpieces as cathodes, a flow gradient by which the electrolyte is driven `at an increased speed through openings or tubes provided in an insulated screen opposite the parts of the cathode which are to be thickened, in order to concentrate the stream lines on such places. sary flow gradient `can be created by increasing the hydrostatic pressure between the anode chamber and the cathode chamber, for example by arranging these chambers at dilerent levels, and/or by means of a pump.

The apparatus of this kind is improved, according to the present invention, by increasing the Velocity of the electrolyte which ows to the parts of the cathodes which are to be thickened, by means of injectors which preferably take the form of tubes or nozzles, thus reducing the scattering of the stream lines emanating from the openings or the like in the screen, and achieving concentration of the ion exchange and increase of the specilic current density on those parts on the workpieces which have t be thickened. The desired local thickening of the galvanic deposit thus takes place more rapidly, more intensively and more precisely than hitherto, this being of particular technological and economical import for the continuous mass processing of such workpieces.

Two devices according to the present invention are illustrated by way of example in the accompanying drawings, in which:

Fig. 1 shows diagrammatically, in vertical longitudinal section, an apparatus with a rotatable anode chamber in the form of a pressure chamber, with which the cathodes are movable.

Fig. 2 shows diagrammatically, in vertical longitudinal section, an apparatus with a pressure-free but rotatable anode chamber disposed above the cathode chamber connected to a space and exerting hydrostatic pressure, the cathodes moving with the anode chamber.

The devices according to Figures 1 and 2 are intended to be used for continuous operation. The cathode chamber 26, which is lilled with the electrolyte uid, is surrounded by an annular tub 25, and surrounds in its turn concentrically an annular container 28 which forms the anode chamber 27 and in which one or several anodes 29 are connected to current leads 30. The cathode chamber 25, in which, if desired, auxiliary anodes 31 with current leads 32 (Fig. 2) can be placed, is connected with the anode chamber 27 by means of a pipe 33 in which can be included a pump 34 in order to keep the electrolyte circulating and, if desired, a lter (not shown in the The neces- Patent drawing). In order' to create -an additional temperature gradient, a heating coil35 4can be installed in the ,anode chamber 27.

In the embodiment according to Fig. 1, the anode chamber 27 is covered by a `pressure-tight lid .37 on a standard 39 and is mounted by means yof ball bearings 38, so as to be rotatable around the vertical middle part -of the pipe 33 which serves as a pivot. The pipe ,33 is connected, within'the Vhollow lid 3.7 and by means of apertures 40, with a duct chamber 41. The cathodes, e. g. the spoons 42, are fastened to the anode container 28 and/ or to its lid 37 by Vmeans of cathode holders 43, rand therefore rotate along with the anode chamber round the central axis ofthe device, and can be easily `put in and taken out at any point on the periphery lof the annular tub 25.

In the embodiment according to Figure 2, an electrolyte chamber 44 is disposed above the cathodeA space 26 and is connected with the anode chamber 27 by means of an annular duct 45. The pipes 33 open into the electrolyte container 44 at its top. The electrolyte which is being circulated by the pump 34, is thus subjected in the anode chamber 27 to a hydrostatic pressure which corresponds to the difference of level of the respective spaces.

According to Fig. 2, the anode chamber 27, with the annular duct 45 and the upper electrolyte chamber 44, are rotatably journallcd on -a central support 46 by means of the ball bearings 47. In a similar manner to the arrangement of Fig. 1, the cathodes 42 are fastened by means of the cathode holders 43, to the wall 48 of the rotatable chambers 27, 45 and 44, and rotate along with the latter.

A diaphragm chamber 52, preferably having an annular shape, is provided between the outer wall of the anode container 28 and the zone of the cathode chamber 26 which contains the cathodes 42. The diaphragm chamber 52 is separated from the cathodes by an insulated diaphragm 53; the latter is provided with apertures, e. g. with nozzles 54, whi-ch open in front of the places on the workpieces 42 which are to be thickened. The diaphragm chamber 52 is connected with the cathode chamber by apertures 55 and 56 provided at the bottom and/ or in the diaphragm wall so that the electrolyte can enter the chamber 52 in the direction indicated by arrows in Figure 2, with the result that essentially the same uid pressure prevails in the chamber 52 and in the cathode chamber 26.

Aperturas with inserted injector nozzles or tubes 57 are provided in the outer wall of the anode container 2S which is contiguous with the diaphragm chamber S2, the said apertures facing the screen apertures or nozzles S4. The injector tubes 57 open a short distance ahead of the inlet ports of the nozzles 54, or else extend to a varying degree into the latter.

I claim:

Apparatus for producing locally thickened galvanic deposits on at least one predetermined surface part of articles inserted in said apparatus as cathodes, said apparatus comprising an anode chamber enclosing at least one anode, a cathode chamber, means for supporting the said articles suspended ascathodes in said cathode charnber, electrical connections serving for connection of said anode and said cathode-supporting means to a source of electric current, an insulated diaphragm arranged between said anode chamber and said cathode chamber and adjacent said articles serving as cathodes in the cathode chamber, said diaphragm having apertures situated opposite the parts of the surface of the articles which are to be provided with a thicker coating concentrating the flux of electrolytic current more strongly on said predetermined surface parts of the articles than on other parts thereof, means adapted to create a pressure drop between the anode chamber and the cathode chamber driving an electrolyte from said anode chamber into said cathode chamber at increased rate of 110W through said apertures in said diaphragmrin ardirection to impingeagainst said predetermined surface parts ofthe artic1es,rrneans adapted for returning the electrolyte from said cathode chamber to said anode chamber, said anode chamber being enclosed in a container provided with said diaphragm having said apertures, a diaphragm chamber'disposed between said insulated diaphragm having said apertures and said anode chamber, said diaphragm chamber communicating with said cathode chamber, said container enclosing said anode chamber dipping into said cathode chamber and being journalled on a support for rotation about a central axis in relation to said cathode chamber, Athe electrolyte being circulated from said cathode chamber by a pump into saidl container, and injector jets connected to said anode chamber, the orifices of said injector jets being directed into said apertures provided with nozzles, the

References Cited in the le of this patent UNITED STATES PATENTS v 1,065,090 Worth June 17, 1913 1,453,419 Thompson May 1, 1923 2,196,355 Cremer Apr. 9, 1940 FOREIGN PATENTS 463,361 Germany Aug. 4, 1928 763,863` France Feb. 19, 1934 887,723 Germany Aug. 27, 1953 888,192 Germany Aug. 31, 1953 

